应用全反射二阶自相关仪测量超短脉冲脉宽

计算了普遍采用的二阶单发自相关仪光路中的分束片的色散引起的超短脉冲展宽量，指出在脉冲极短时该展宽将导致不准确的测量结果(例如，对于脉冲宽度为3fs左右，通过100μm厚度的K9玻璃分束片，脉冲展宽将达到10％)。基于计算结果，提出了一种新型的采用全反射结构的单发二阶自相关仪设计，通过分波面的方法改变了自相关仪的分束方式，避免了采用透射分束光学元件引起的色散。采用这种全反射式结构的二阶单发自相关仪，可以使自相关测量方法测得的脉冲宽度更为准确，计算得出理论上其最小时间分辨率可达3．6fs。

Measure Ultrashort Pulsewidth with Total Reflection Second-Order Autocorrelator

The expanding of the pulse duration due to the dispersion of the beam splitter adopted in normal single-shot second-order auto-correlator (SSA) was calculated. It is shown that, for ultra-short pulses, this kind of pulse-expanding will introduce imprecision of the result (e.g., for a pulse with the duration of about 3 fs, the expanding of a 100 μm thick beam-splitter of K9 glass is 10%). Based on these results, a kind of total-reflection single-shot auto-correlator is proposed. Via changing the beam splitting method from wave-front splitting to wave-surface splitting, the dispersion of the beam-splitter is avoided. By adopting this kind of SSA, the accuracy of the measurements for ultrashort pulses is improved. The calculated results show that the accuracy is about 3.6 fs.